Stimulation of wells through mechanical fracturing can be accomplished by a method known as controlled pulse fracturing or high energy gas fracturing. A good description of this method appears in an article by Cuderman, J. F., entitled "High Energy Gas Fracturing Development," Sandia National Laboratories, SAND 83-2137, October 1983. Using this method enables the multiple fracturing of a formation or reservoir in a radial manner which increases the possibility of contacting a natural fracture. In the practice of this method, a canister or molded body containing a propellant is suspended into a wellbore. This canister is placed downhole next to the oil or hydrocarbonaceous fluid productive interval.
The propellant in the canister or molded body can belong to the modified nitrocellulose or the modified and unmodified nitroamine propellant class. Suitable solid propellants capable of being utilized include a double-based propellant known as M-5. It contains nitroglycerine and nitrocellulose. Another suitable propellant is a composite propellant which contains ammonium perchlorate in a rubberized binder. The composite propellant is known as HXP-100 and is purchasable from the Holex Corporation of Hollister, Calif. M-5 and HXP-100 propellants are disclosed in U.S. Pat. No. 4,039,030 issued to Godfrey et al. which is hereby incorporated by reference.
After placing the propellant means for creating multiple fractures into a canister and suspending it downhole near all the oil or hydrocarbonaceous fluid productive interval, it is ignited. Ignition of the propellant means for creating the multiple fractures causes the generation of heat and gas pressure. To contain the generated propellant energy within the wellbore and formation, an aggregate stem, generally composed of cement, is placed above the canister or molded body containing the propellant thereby sealing the wellbore. The canister suspension and ignition means passes through the aggregate stem.
After ignition of the propellant means it is difficult to remove the aggregate stem, which often has to be drilled out. When removing the aggregate stem, the suspension means, generally a cable, and the ignition means, along with remnants of the canister which previously contained the propellant, frequently fall into the wellbore. This debris may interfere with production of hydrocarbonaceous fluids from the formation. Drilling out the aggregate often damages the wellbore and formation.
Therefore, what is needed is a method to reduce the vertical drag on downhole equipment used during a CPF operation so as to avoid damaging said equipment and formation.